The present invention relates generally to electrical switch devices, and more particularly, to a pneumatic actuated electrical switch that is responsive to a vacuum exerted thereon.
Pneumatic actuated switches are used in applications where it is desirable to actuate an electrical component at a remote location in response to a change in pressure, generally at a remote source. Such switches typically have a diaphragm assembly disposed adjacent to an electrical switch. The diaphragm assembly includes a resilient diaphragm element disposed adjacent a pressure chamber. The diaphragm element is designed to move and actuate the switch in response to a change in pressure in the pressure chamber. In general, the pressure chamber is connected by a circuit or channel, typically tubing, to a remote pressure source. The actuator and circuit or channel leading up to the pressure chamber are airtight to insure transfer of a pressure pulse from an actuator or a pressure source into the pressure chamber.
As with most electrical components, there have been ongoing efforts to reduce the size and cost of such switches, while at the same time maintaining or enhancing their performance. As the size and number of components in a switch become smaller and smaller, positioning and maintaining alignment of the operative components during assembly of the switch, and later during operation of the switch, become more important. In this respect, a pneumatic actuated switch is typically assembled by hand, and is generally enclosed within a housing in such a fashion that it is difficult to determine if the switch components are properly aligned during assembly and during operation, i.e., when the housing is closed or sealed.
The present invention provides a vacuum actuated pressure switch having internal components dimensioned to align themselves along a switch axis during assembly and operation.
In accordance with a preferred embodiment of the present invention, there is provided a pressure switch comprising a housing having a pressure chamber, a port communicating with the pressure chamber and a recessed throat located where the port communicates with the chamber. A flexible diaphragm is disposed within the housing adjacent the pressure chamber, and an electric switch is mounted to the housing. A pressure plate is disposed between the diaphragm and the port. The pressure plate has a first surface contoured to mate with a portion of the diaphragm and a second surface facing the port having a plurality of projections extending from the second surface. The projections are dimensioned to engage the throat portion and maintain the second surface therefrom. The projections define passageways where the port communicates with the chamber when the projections engage the throat.
In accordance with another aspect of the present invention, there is provided a pressure switch comprising a housing having an upper housing section and a lower housing section. The lower housing section has a port extending therethrough and a contoured surface surrounding the port. A diaphragm disposed within the housing is captured between the upper housing section and the lower housing section. The diaphragm defines a pressure relief chamber with the upper housing section, and a pressure chamber with the lower housing section. The diaphragm is formed of a flexible material and has a neutral, unflexed configuration. A pressure plate is disposed between the diaphragm and the port. The pressure plate has a first surface contoured to mate with a portion of the diaphragm. A second surface faces the port and has a projection extending from the second surface. The projection is dimensioned to engage the contoured surface and to maintain the second surface therefrom. The projection defines a passageway wherein the port communicates with the chamber when the projection engages the contoured surface.
It is an object of the present invention to provide a vacuum actuated electrical switch.
Another object of the present invention is to provide a switch as described above having intemal components with surface features that self align the components along a switch axis during assembly and maintain alignment of the components during operation.